is there to define the variables i and j as integer (-i) (equivalent to int i,j; in c)

The next line is parsing the file, and looping each line between the “do” and “done”. The line is put in the variable “line”

If you had written

cat tempo1 | while read JamesTKirk

then the variable containing the line would have been JamesTKirk, which is a bit long to type and also a bit of an overkill to have one of the best Starfleet Captain as your variable.

Next line speaks by itself :

if echo $line | grep COMP >/dev/null 2>&1; then

means “if the result of the command “echo $line | grep COMP” is 0, then execute the following” and of course, this will only be the case if the line in question contains the word “COMP” somewhere. We could have done maybe with “grep -e ‘^COMP'”, or with the funny test we’ll see tomorrow, but let’s not split the hair.

i=`expr \`echo $line | cut -f2- -d’ ‘\“

expr allows you to do basic arithmetical calculation. This line means “Take everything after the first field on the line, space being the separator, then compute it and store it in the variable “i”“.

let j=j+i

let is another way to do arithmetical operations, using integer variables.

and voila, done.

Should you require more assistance, feel free to post in the comments or to man the command you want to know about.

Thank you for reading, and see you tomorrow for a special test operator.